Punching bag



FIG. 1 is a perspective view of the punching bag showing my new design;

FIG. 2 is a front elevation view thereof; the rear elevation view being a mirror image thereof;

FIG. 3 is a right side elevation view thereof; the left side elevation being a mirror image thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof.

The broken lines shown in the drawings illustrate portions of the punching bag that form no part of the claimed design. 

CLAIM The ornamental design for a punching bag, as shown and described. 